XBee is the brand name from Digi International for a family of form factor compatible radio modules. The first XBee radios were introduced under the MaxStream brand in 2005[2] and were based on the 802.15.4-2003 standard designed for point-to-point and star communications at over-the-air baud rates of 250 kbit/s.[3]

Two models were initially introduced—a lower cost 1 mW XBee and the higher power 100 mW XBee-PRO.[4] Since the initial introduction, a number of new XBee radios have been introduced and all XBees are now marketed and sold under the Digi brand.

The XBee radios can all be used with the minimum number of connections – power (3.3 V), ground, data in and data out (UART), with other recommended lines being Reset and Sleep.[5] Additionally, most XBee families have some other flow control, I/O, A/D and indicator lines built in. A version of the XBees called the programmable XBee has an additional onboard processor for user’s code. The programmable XBee and a new surface mount (SMT) version of the XBee radios were both introduced in 2010.[6]

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XBee Modules are available in two form-factors; through-hole and surface mount (SMT). All XBees (with the exception of the XBee 868LP) are available in the popular 20-pin Through-Hole form-factor. Certain XBee modules are also available in a 37-pad Surface Mount design, which is popular for higher volume applications due to the reduced manufacturing costs of SMT.

The XBees can operate either in a transparent data mode or in a packet-based application programming interface (API) mode.[8] In the transparent mode, data coming into the Data IN (DIN) pin is directly transmitted over-the-air to the intended receiving radios without any modification. Incoming packets can either be directly addressed to one target (point-to-point) or broadcast to multiple targets (star). This mode is primarily used in instances where an existing protocol cannot tolerate changes to the data format. AT commands are used to control the radio’s settings. In API mode the data is wrapped in a packet structure that allows for addressing, parameter setting and packet delivery feedback,[9] including remote sensing and control of digital I/O and analog input pins.[10]